This invention generally relates to a device for delivering drugs to hollow body organs such as the urinary system, the female reproductive system, the anal tract, or the ear, nose or throat. In particular, the invention is specially suited for treatment of the prostate gland.
The term "drug" as used herein is used in its broadest sense and can be diagnostic agents such as radiopaque visualizing agents for use in x-ray or fluoroscopic techniques or may be antibiotic, chemotherapy or other materials used to treat the body.
For example, disfunction or diseases of the prostate gland, an organ within the male urinary system, can be treated by systemic delivery of therapeutic agents. However, these agents must be delivered in high doses when given systemicly or they will not be effectively delivered to the prostate. In addition, these therapeutic agents can be very toxic to the body as a whole causing unwanted side effects. The preferred procedure is to deliver the drug directly to the prostate gland. This is difficult because of the small size of the prostate and the inaccessible location of the gland. The best procedure is to introduce the drugs into the prostate ducts which are accessible through the urethra at a point close to its entry into the bladder.
Several devices have been proposed for delivery of drugs to body organs. Devices for accessing the prostatic ducts all have deficiencies which limit their applicability. Latex, silicone or other polymer based catheters of the Foley design have been proposed for delivering the drugs. One proposal is to place grooves or channels on the outer surface of the catheter so that fluids used to irrigate the bladder can be allowed to wash the outer surface of the catheter and the wall of the urethra. This defeats the purpose of the Foley catheter as it allows leakage of urine from the bladder and establishes a path for retrograde infection. Merrill, U.S. Pat. No. 4,055,682, has disclosed techniques for coating a silicone catheter with a hydrophilic polymer such as N-vinyl pyrrolidone, hydroxy ethyl methacrylate or combinations thereof. Gould discloses in U.S. Pat. No. 4,156,067 the application of hydrophilic polyurethane polymers to the surface of catheters. The hydrophilic coatings on these catheters can be used as carriers for the delivery of water soluble drugs. These drugs are blended into the coatings before they are applied to the catheter or the region of the catheter which would be placed adjacent to the prostatic ducts can be dipped into the desired therapeutic agent before the catheter is placed in the urethra. However, there is a problem controlling the rate of delivery of the drug and the dosage level with such a device and the catheter must be removed and replaced periodically if the drug is to be replenished. Every time a catheter is removed and replaced the chance of introducing infectious agents increases.
U.S. Pat. No. 3,977,408 issued to MacKew discloses a Foley catheter with an extra conduit the proximal end of which exits through the wall of the catheter at a point which is positioned adjacent the area of the prostate when the catheter is positioned in the urethra. This allows the delivery of medication directly to a single point along the urethra. There is no way of controlling the exact point for delivery of drugs, to assure that the drug is dispersed around the full 360.degree. of the urethra, or to reliably restrict the drug delivered from disbursing along the length of the urethra and leaking out of the penis. It is suggested that a clamp on the penis be used but this is uncomfortable to the patient and would crush the delivery and drainage lumen preventing delivery of the drug and drainage of urine from the bladder. This is a major deficiency as it may be necessary for certain drugs, such as chemotherapy agents, to be delivered continuously over a period of days, weeks, or even months.
While the prior art has attempted to address the problem of delivering drugs to the prostate gland, the prior art devices do not address all the problems, are inefficient, cause new problems, and do not allow a controlled continuous delivery of drugs.